Bootstrap/Rails - String Interpolation inside accordion - ruby-on-rails

Question

I've been struggling with string interpolation inside an HTML accordion. It's more a logic issue that I can't seem to figure out (fairly new to rails). The problem I have is that while the layout is fine, when I click to collapse any of the 3 collapsible panels they all collapse. (Because I only have 1 #collapse).
Outermost ERB
<div class="container-fluid">
<div class="row">
<div class="col-md-2 col-sm-3">
<h2>Categorias</h2>
<div class="panel-group" id="accordion">
<%= render partial: "categories/catalog", collection: #categories, as: :c %>
</div>
</div>
_catalog Partial
<div class="panel panel-default">
<div class="panel-heading">
<h4 class="panel-title">
<a data-toggle="collapse" data-parent="#accordion" href="#collapse1">
<%= c.name %>
<span class="badge">4</span>
</a>
</h4>
</div>
<div id="collapse1" class="panel-collapse collapse in">
<% c.subcategories.each do |sc| %>
<div class="panel-body">
<a href="#">
<%= sc.name %>
</a>
</div>
<% end %>
</div>
</div>
Controller
def catalogo
#categories = Category.where("parent_id IS NULL")
unless params[:cat_id].blank?
#products = Product.where(category_id: params[:cat_id]).paginate(:page => params[:page], :per_page => 50)
else
#products = Product.all.paginate(:page => params[:page], :per_page => 50)
end
#categorieswparent = Category.where("parent_id IS NOT NULL")
end

Answer 1

Your IDs need to be unique. Instead of hard-coding id="collapse1", use the ID of the record:
id="collapse<%= sc.id %>"
Perform the same interpolation for the href of the <a> tag responsible for collapsing and expanding the accordion.

Answer 2

Use category id id="#collapse<%= c.id %>" to interpolate with element id in _catalog Partial.
<div class="panel panel-default">
<div class="panel-heading">
<h4 class="panel-title">
<a data-toggle="collapse" data-parent="#accordion" href="#collapse<%= c.id %>">
<%= c.name %>
<span class="badge">4</span>
</a>
</h4>
</div>
<div id="collapse<%= c.id %>" class="panel-collapse collapse in">
<% c.subcategories.each do |sc| %>
<div class="panel-body">
<a href="#">
<%= sc.name %>
</a>
</div>
<% end %>
</div>
</div>